Welcome to the World of Memory: Eyewitness Testimony
Ever witnessed something and tried to describe it later, only to realize you weren't quite sure of the details? In Psychology, this is called Eyewitness Testimony (EWT). It refers to the evidence provided by people who witnessed a crime or an event, often based on their memory of what happened. While it sounds reliable, memory is a lot more "fragile" than we think!
In this chapter, we will explore why eyewitnesses sometimes get things wrong and how police can use a special technique called the Cognitive Interview to get better results. This is a vital part of your Paper 1: Memory syllabus.
Factor 1: Leading Questions
A leading question is a question that, because of the way it is phrased, suggests a certain answer. It "leads" the witness to think a certain way.
How it works: Our memories aren't like video recordings; they are reconstructive. When we are asked a leading question, the misleading information can actually change our original memory of the event. This is often called the substitution explanation.
Example: Imagine you saw a car accident. If a lawyer asks, "How fast was the car going when it smashed into the other car?" vs "How fast was the car going when it hit the other car?", the word "smashed" suggests a much higher speed. You might "remember" seeing broken glass even if there wasn't any, simply because the word "smashed" led you there.
Key Takeaway: The specific words used in a question can distort a person’s memory of an event.
Factor 2: Post-Event Discussion (PED)
Post-event discussion happens when witnesses to a crime discuss what they saw with each other before they are interviewed. This can seriously damage the accuracy of their testimony.
There are two main reasons why this happens:
1. Memory Contamination: Witnesses mix (combine) information from other people with their own original memories. They start to "remember" things they didn't actually see.
2. Memory Conformity: Witnesses go along with each other to win social approval or because they believe the other person is right and they are wrong. Their actual memory doesn't change, but their report of it does.
Did you know? Even a small conversation between two witnesses can lead to them reporting the same errors in court!
Factor 3: Anxiety
Anxiety is a state of emotional and physical arousal. It includes feelings of tension and increased heart rate. Interestingly, anxiety can have both a positive and a negative effect on memory.
The Negative Effect: Weapon Focus
When a crime involves a weapon (like a knife or a gun), witnesses often focus all their attention on the weapon because it is the source of danger and anxiety. This means they fail to notice other details, like the criminal's face. This is known as Weapon Focus.
The Positive Effect: Fight or Flight
Some researchers argue that high anxiety triggers the "fight or flight" response, which actually makes us more alert. This increased alertness can improve our memory for the event because we are more "tuned in" to what is happening.
The "Inverted-U" Theory
Psychologists use the Yerkes-Dodson Law to explain this. It suggests that the relationship between anxiety and accuracy looks like an upside-down "U":
- Low Anxiety: Accuracy is low (we aren't paying enough attention).
- Medium Anxiety: This is the "optimal" level where accuracy is highest.
- High Anxiety: Accuracy drops significantly (we are too stressed to process details).
Quick Review: Think of it like a sports game. If you aren't nervous at all, you might play poorly. If you are terrified, you might freeze. You need that "just right" amount of nerves to perform your best!
Improving Accuracy: The Cognitive Interview
Standard police interviews used to be very "bullet-point" style, often interrupting witnesses and asking short, closed questions. To fix this, psychologists developed the Cognitive Interview (CI). It is based on our understanding of how memory works.
There are four main techniques used in the Cognitive Interview:
1. Report Everything
The witness is encouraged to include every single detail, even if it seems irrelevant or they aren't confident about it. Small details might act as "triggers" for more important memories.
2. Reinstate the Context
The witness should return to the crime scene "in their mind." They are asked to imagine the environment (the weather, what it looked like) and their emotions (how they felt). This is based on context-dependent forgetting—we remember things better when we are in the same environment/state as when the memory was formed.
3. Reverse the Order
The witness is asked to describe the event in a different chronological order (e.g., from the end back to the beginning). This prevents people from reporting their expectations of what usually happens (their "schemas") and makes it harder for them to lie.
4. Change Perspective
The witness is asked to recall the incident from the perspective of another person present (e.g., another witness or the victim). This also helps to disrupt the effect of schemas on recall.
Memory Aid: The "4 Pillars" of CI
To remember these, think: E.C.O.P.
E - Everything (Report everything)
C - Context (Reinstate context)
O - Order (Reverse the order)
P - Perspective (Change perspective)
Common Mistakes to Avoid
Don't confuse Leading Questions with Post-Event Discussion:
- Leading Questions are about the interviewer influencing the witness.
- Post-Event Discussion is about other witnesses influencing the witness.
Don't forget the math:
In the exam, you might see data about EWT. Remember that significance is usually measured at the \(p \leq 0.05\) level. This means there is a less than \(5\%\) probability that the results happened by chance.
Evaluation Hint: While the Cognitive Interview is great, it is time-consuming and requires specialist training, which many police forces find difficult to provide.
Summary Checklist
- Can you define a leading question?
- Can you explain how PED contaminates memory?
- Can you describe the "Inverted-U" relationship between anxiety and memory?
- Do you know the 4 stages of the Cognitive Interview?
Keep practicing! Memory is one of the most relatable topics in Psychology—use your own experiences to help you remember the concepts!